Observation of optical inhomogeneities in flux grown KTP crystals

Optical inhomogeneities in potassium titanyl phosphate crystals grown from different fluxes have been investigated. In the crystals grown from a flux which contains tungsten, striations parallel to the {011} faces were observed. The main reason for forming striations is the change in tungsten concentration with change in growth rate. In the case of a potassium phosphate flux, no striations were observed in the crystal which was grown at almost the same temperature and stirring conditions as for the tungstate flux. We can conclude that the phosphate flux is more suitable for the growth of optically good crystals for KTP as laser harmonic converters.     

Kinetics of the Same Reaction Monitored over Nine Orders of Magnitude in Concentration: When Are Unique Subensemble and Single‐Turnover Reactivity Displayed?

Essentially no information is known about the behavior of individual molecular catalysts under reaction conditions. This is a result of the averaging inherent to traditional analytical techniques. Herein, a combined fluorescence microscopy and ¹H NMR spectroscopy study reveals that unique (that is, non‐ensemble averaged) distributions and time‐variable kinetics from molecular ruthenium catalysts within growing polynorbornene occur and are detectable between 10^?9 m and 10^?6 m of substrate, surprisingly just 1000‐fold less concentrated than a typical laboratory bench‐scale reaction. The kinetic states governing single‐turnover events are determinable by overlay of the signal arising from individual monomer insertion reactions with that from polymer growth from neighboring catalysts.     

Synthesis of 3-(1-hydroxyalkyl)-4,5,6,7-tetrahydroindazole derivatives. Structure determination of N-alkyl isomers

A novel series of 3-(1-hydroxyalkyl)-4,5,6,7-tetrahydroindazoles and their 1 and 2-alkyl-3-(1-hydroxyalkyl)-or-3-(1-acetoxyalkyl) derivatives were synthesized via condensation between 3-oxo-2,3,4,5,6,7-hexahydrobenzo[b]furans or 2-(2-acetoxyacyl)cyclohexanones and hydrazines. Structure assignment are based on ¹H and ¹³C nmr spectra.     

Observations sur l'emploi des compteurs à cathode externe pour le dosage du tritium

Résumé Dans l'utilisation des compteurs Geiger-Müller du type Maze pour l'analyse des substances organiques tritiées, l'auteur observe trois types de perturbations: il indique qu'ils proviennent respectivement de traces d'oxygène, de traces de vapeur de mercure et d'une modification de l'état de surface du verre constituant la coque du compteur et les précautions à prendre pour les éviter.

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Summary When using Geiger-Müller counters of the Maze type in the analysis of organic materials containing tritium, the author has observed three types of disturbances. She points out that they arise respectively from: traces of oxygen, traces of mercury vapor, and from the modification of the state of the glass surface constituting the shell of the counter. The precautions needed to avoid these faults are stated.

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Zusammenfassung Bei der Verwendung von Geiger-Müller-Zählern (Typus Maze) für die Analyse tritiumhältiger organischer Substanzen konnten drei Arten von Störungen beobachtet werden. Sie werden durch Sauerstoffspuren, Quecksilberdampfspuren oder durch eine Zustandsänderung der Oberfläche der Schale des Zählgerätes verursacht. Die zur Vermeidung dieser Fehler geeigneten Maßnahmen werden angegeben.

     

Synthesis of some 4-acetyl-3,5-dioxo-2,3,4,5-tetrahydro[1]benzoxepine or benzothiepine and 6-acetyl-5,7-dioxo-6,7,8,9-tetrahydro-5H-benzocycloheptene derivatives

The title compounds were prepared from benzoxepino-, benzothiepino- or benzocycloheptaisoxazolones which in turn were synthetized from simple materials.     

Preparation and properties of a new type of comb-shaped, amphiphilic cellulose derivative

Comb-shaped, amphiphilic O-(2- hydroxy-3-butoxypropyl) cellulose (HBPC) was prepared by a homogeneous reaction of cellulose with butyl glycidyl ether (BGE) in a 10% (w/w) LiCl--DMAc solution. It was found that: (a) the molar substitution (MS) of water-soluble HBPC ranges from 0.4 to 1.0, and is nearly equal to its degree of substitution (DS), indicating that the HBPC derivatives obtained are comb-shaped polymers; (b) the water-soluble HBPC shows a thermally reversible sol-gel transition in aqueous solution; and (c) the derivative having a DS of 0.6 shows surface activity with critical micelle concentration (cmc) in the order of 0.8 g/l and surface tension of 31.5 dyn/cm     

Zeolite membrane on catalyst particles for selective formation of p-xylene in the disproportionation of toluene

The selective formation of p-xylene is shown in toluene disproportionation using a new catalyst which is surrounded with a permselective membrane.